Physics Unit 1

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  • Created by: Lottie_C
  • Created on: 28-03-16 11:31
what will happen if there is a difference in temperature?
energy will flow between them
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particles in a solid
strong forces of attraction, close together, regular arrangement, vibrate around fixed position
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particles in a liquid
weaker forces of attraction, close together, irregular arrangement, move around each other as have more energy
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particles in a gas
almost no forces of attraction, far apart, random arrangement, more energy ,free to move in any direction
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conduction
conduction of heat is process of vibrating particles passing on kinetic energy to neighbouring particles
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free electrons
metals, free to move inside the metal, help metals to conduct heat
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convection
particles with lots of heat energy move and take the place of particles with less heat energy, liquid/gas
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convection currents
heat transferred from place to place
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thermal radiation
all objects emit and absorb radiation. the hotter the object is, the more radiation it radiates in a given time
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light shiny surfaces
poor at emitting/absorbing radiation, silvered surfaces good at reflecting
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dark matt surfaces
good at emitting/absorbing radiation
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condensation
when a gas cools, particles slow down and lose kinetic energy, the forces pull them close together and the gas becomes a liquid
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increase rate of condensation by
temperature of gas decreases
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evaporation
particles escape from a liquid if they are travelling in right direction and fast enough to overcome attractive forces
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increase rate of evaporation by
increasing temperature of liquid, surface area of liquid, air moving over surface of liquid
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why does a liquid cool as it evaporates
faster particles more likely to evaporate, average speed and kinetic energy of remaining particles decrease, temperature of remaining liquid falls
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thermal expansion
particles vibrate more when heated so they take up more space
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how do vacuum flasks limit heat transfer
glass bottle is double walled with vacuum (stops conduction and convection through sides), walls are silvered (minimises heat loss by radiation), bottle supported using insulated foam (minimises heat conduction)
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how do arctic foxes small ears limit heat transfer
small surface area minimises heat loss by radiation and conserves body heat
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how do desert foxes big ears increase heat transfer
large surface area maximises heat loss by radiation
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how to insulate a house (5)
cavity wall insulation, loft insulation, draught proofing, hot water tank jacket, thick curtains
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u-values
materials with higher u-value transfer heat faster. the better the insulator, the lower the u-value
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specific heat capacity
amount of energy needed to raise the temperature of 1kg of a substance by 1 degree celsius
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payback time
measure of how cost effective something is
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types of energy (9)
electrical, light, sound, kinetic, nuclear, thermal, gravitational potential, elastic potential, chemical
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stored energy
potential energy can be stored
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conservation of energy principle
energy can be transferred usefully from one form to another but never created or destroyed
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efficiency of a machine
how good it is at transferring energy usefully, no device is 100% efficient
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sankey diagrams
width represents amount of energy, useful and wasted is same as total input
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renewable resources
used over and over again
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examples of renewable resources
solar, wind, hydroelectric, wave, tidal, biofuels, geothermal
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non renewable resources
once energy released, cannot be used again, provide most of our energy
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examples of non renewable resources
fossil fuels (coal, oil, natural gas) and nuclear
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thermal power station
heat from fuel turns turbine, turbine turns generator, produces electricity, goes to national grid, waste heat to surroundings
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Nuclear reactors
nuclear fission of uranium or plutonium produces heat to make steam to turn turbines
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advantages of nuclear reactors (3)
release more energy than chemical reactions, doesn't produce carbon dioxide, nuclear fuel quite cheap
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disadvantages of nuclear reactors (4)
radioactive waste (difficult to dispose of and dangerous), puts people at risk of irradiation/contamination, extra safety precautions, longest start up time
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pumped storage
surplus night time electricity is used to pump water to a higher reservoir which can be released quickly during peak demand
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environmental problems with non renewable resources (2)
fossil fuels release carbon dioxide when burned, coal and oil release sulphur dioxide (acid rain)
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carbon capture
traps carbon released and buries it underground
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national grid
UK mains electricity supply, takes energy from power stations to homes/industry
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stepping up power
voltage stepped up to power lines, same power can be transmitted using lower current, less heat energy lost, voltage stepped down to safe level for consumers, system efficient
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supply and demand
energy demands increasing constantly, to meet demands energy supplied needs to increase (more power plants) or demand needs to decrease (not wasting energy)
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wave
flow of energy due to vibration of variation
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longitudinal wave and examples (2)
vibration parallel to direction of propagation, seismic or sound
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transverse wave and examples (2)
vibration is perpendicular to direction of propagation, seismic or light
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amplitude
maximum displacement
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wavelength
distance between two consecutive waves
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time period
time taken for one complete cycle
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frequency
number of cycles per second
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law of reflection
angle of incidence equal to angle of reflection
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normal
imaginary line perpendicular to surface at point of incident angle
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properties of reflected image
virtual image, object and image same distance from mirror, image laterally inverted, object and image same size
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law of refraction
when light enters denser medium, it slows and bends towards normal so incident angle is bigger than refracted angle
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diffraction
spreading out of waves as they pass through gap or go past an obstacle, most pronounced if gap size equals wavelength
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sound waves
can't travel through vacuum, reflected by hard surfaces (echo), will also refract
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Electromagnetic waves
can travel through a vacuum, travel at speed of light
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types of EM waves (7)
radio waves, microwaves, infra red, visible light, ultraviolet, x-rays, gamma
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radio waves uses (1)
radios
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micro waves uses (2)
satellite communication and phones
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infrared waves (1)
remote controls
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visible light (1)
photography
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gamma ray uses (1)
medecine, treat cancer
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Doppler effect
apparent change in the frequency of a wave caused by the relative motion between the source of the wave and the observer
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red shift
light source moving away from you as moves to red end of spectrum
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blue shift
source moves towards you
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Big Bang Theory
everything in universe exploded from single point 13 million years ago,red shift shows universe expanding, suggesting it must be expanding from somewhere
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evidence for red shift
when observing light from stars/galaxies, we see red shift. suggest they're moving away from us, more distant objects have more red shift so moving faster, evidence universe exanding
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CMBR
cosmic micro wave background radiation, explained by Big Bang Theory,
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Other cards in this set

Card 2

Front

particles in a solid

Back

strong forces of attraction, close together, regular arrangement, vibrate around fixed position

Card 3

Front

particles in a liquid

Back

Preview of the front of card 3

Card 4

Front

particles in a gas

Back

Preview of the front of card 4

Card 5

Front

conduction

Back

Preview of the front of card 5
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Comments

georgiaxla

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how do u work this

georgiaxla

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nvm

AliceGallard09

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woop

AliceGallard09

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its my birthday

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